Caps equipped with a mechanism for ejecting a content liquid out of a container in a foamy state (i.e., foam dispensing caps) have so far been known. These caps are applied to containers, such as bottles, where seasonings, foods, beverages, cleaning agents, or cosmetics, for example, are accommodated.
With such a foam dispensing cap, the content liquid has to be mixed with air, and then ejected from the container. Thus, the publicly known foam dispensing cap is provided with a tube not for discharging air inside the container (air present in a head space) immediately out of the container in ejecting the content liquid, but for once taking in this air and mixing it with the content liquid, or a tube for discharging the content liquid in such a manner as to be mixable with the air inside the container. Such a tube is very long (see, for example, Patent Documents 1 and 2).
The foam dispensing cap provided with the above-mentioned tube, however, poses the problem that a capping operation for mounting this cap on the mouth of the container is extremely troublesome. That is, such a tube is not only long, but is also highly flexible, thus making it very troublesome to perform, for example, alignment for passing the tube through the container mouth having a small diameter.
A foam dispensing cap without such a tube has also been proposed (see Patent Document 3).
Such a foam dispensing cap is mounted with a small bubble generation sheet of a Teflon (registered trademark)-coated cloth or the like, and the container content liquid and air present in the head space of the bottle are discharged through the sheet to eject the content liquid in a foamy state.
The cap of Patent Document 3 mentioned above is not mounted with a particular tube. Thus, a capping operation for mounting the cap on the mouth of the container is very easy, but involves the problem of a noticeably low foam dispensing function. That is, air necessary for generation of air bubbles is discharged very quickly when the container is tilted and squeezed. As a result, a tiny amount of the content liquid ejected initially is the only foam dispensed.